docs: def diameter_ratio_wedge_meter(D, H):
      r'''Calculates the diameter ratio `beta` used to characterize a wedge 
      flow meter as given in [1]_ and [2]_.
      
      .. math::
          \beta = \left(\frac{1}{\pi}\left\{\arccos\left[1 - \frac{2H}{D}
          \right] - 2 \left[1 - \frac{2H}{D}
          \right]\left(\frac{H}{D} - \left[\frac{H}{D}\right]^2
          \right)^{0.5}\right\}\right)^{0.5}
          
      Parameters
      ----------
      D : float
          Upstream internal pipe diameter, [m]
      H : float
          Portion of the diameter of the clear segment of the pipe up to the 
          wedge blocking flow; the height of the pipe up to the wedge, [m]
      
      Returns
      -------
      beta : float
          Wedge meter diameter ratio, [-]
  
      Notes
      -----
      
      Examples
      --------
      >>> diameter_ratio_wedge_meter(D=0.2027, H=0.0608)
      0.5022531424646643
      
      References
      ----------
      .. [1] Hollingshead, Colter. "Discharge Coefficient Performance of Venturi,
         Standard Concentric Orifice Plate, V-Cone, and Wedge Flow Meters at 
         Small Reynolds Numbers." May 1, 2011. 
         https://digitalcommons.usu.edu/etd/869.
      .. [2] IntraWedge WEDGE FLOW METER Type: IWM. January 2011.
         http://www.intra-automation.com/download.php?file=pdf/products/technical_information/en/ti_iwm_en.pdf
      '''
      H_D = H/D
      t0 = 1.0 - 2.0*H_D
      t1 = acos(t0)
      t2 = 2.0*(t0)
      t3 = (H_D - H_D*H_D)**0.5
      t4 = t1 - t2*t3
      return (1./pi*t4)**0.5